The bacterium which causes whooping cough, Bordatella pertussis, has a uniquely crystalline outer membrane. In order to produce better vaccines, FDA scientists have purified the major protein from this membrane. This purified protein porin forms large, conducting channels in planar bilayers which are selective for anions over cations. Members of the PSL are currently testing various kinetic models for this behavior. Membrane transport was used to measure the dipole potential of lipids. Planar phospholipid membranes were prepared of either DPPC or DHPC, which differ by the presence of the ester-linked carbonyl groups. The conclusion of this investigation is that the dipole potential cannot cause the hydration force